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<TITLE>Magic-8.3 Command Reference</TITLE>
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<H1> <IMG SRC=graphics/magic_title8_3.png ALT="Magic VLSI Layout Tool Version 8.3">
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<H2>drc</H2>
<HR>
Background design rule checker control and status.
<HR>

<H3>Usage:</H3>
   <BLOCKQUOTE>
      <B>drc</B> <I>option</I> <BR><BR>
      <BLOCKQUOTE>
         where <I>option</I> is one of the following:
	 <DL>
	   <DT> <B>catchup</B>
	   <DD> Run checker and wait for it to complete
	   <DT> <B>check</B>
	   <DD> Recheck area under box in all cells
	   <DT> <B>count</B>
	   <DD> Count and report error tiles in the edit cell.
	   <DT> <B>euclidean on</B>|<B>off</B>
	   <DD> Enable/disable Euclidean geometry checking
	   <DT> <B>find</B> [<I>nth</I>|<I>text</I>]
	   <DD> Locate next (or <I>nth</I>) error in current cell;  if string
		<I>text</I> is given instead of an integer, then search for the
		next error of a type containing the text.
	   <DT> <B>help</B>
	   <DD> Print help information
	   <DT> <B>ignore</B> [<I>text</I>|<B>none</B>]
	   <DD> Without options, print a list of all rules that are not being
		reported.  With option <I>text</I>, don't report rules containing
		the string <I>text</I>.  This is cumulative;  additional calls
		to "<B>drc ignore</B> <I>text</I>" will add rules to be ignored.
		Cancel ignoring rules with "<B>drc ignore none</B>" (the default).
	   <DT> <B>off</B>
	   <DD> Turn off background checker
	   <DT> <B>on</B>
	   <DD> Reenable background checker
	   <DT> <B>status</B>
	   <DD> Report whether the background checker is on or off.
	   <DT> <B>printrules</B> [<I>file</I>]
	   <DD> Print out design rules in <I>file</I> or to <TT>stdout</TT>
	   <DT> <B>rulestats</B>
	   <DD> Print out statistics about design rule database
	   <DT> <B>statistics</B>
	   <DD> Print out statistics gathered by checker
	   <DT> <B>why</B>
	   <DD> Print out reasons for errors under box
	   <DT> <B>*halo</B> [<I>value</I>]
	   <DD> Without option <I>value</I>, prints out the DRC halo distance,
	   	which is the largest distance at which a DRC interaction can
		occur outside of any area to be checked.  Becuase large DRC
		haloes can cause very long delays in the interactive DRC
		checks, it can be helpful to use <I>value</I> to force a
		smaller halo.  This causes certain DRC errors to be missed,
		but allows all the basic short-distance design rules to be
		checked without undue processing delays.
	   <DT> <B>*stepsize</B> [<I>value</I>]
	   <DD> The step size is the length of a side of the area into which
		the DRC checker routine breaks up larger areas for more
		efficient processing.  Changing this value can greatly
		effect the speed of the DRC checker, although it is
		difficult to predict what step size is "optimal".  Without
		option <I>value</I>, returns the current value of the
		step size.
	 </DL>
      </BLOCKQUOTE>

      <P>
      The Tcl/Tk version of magic defines additional handling with the
      "<B>list</B>" and "<B>listall</B>" keyword before the option name,
      indicating that the information be passed back to the interpreter
      as a list instead of being printed to the terminal window as text.
      <P>

      <B>drc list</B> <I>option</I> <BR><BR>
      <BLOCKQUOTE>
         where <I>option</I> is one of the following:
	 <DL>
	   <DT> <B>style</B>
	   <DD> Return the currently active DRC style name to the interpreter.
	   <DT> <B>count</B> [<B>total</B>]
	   <DD> Return the DRC error count as a list pair comprising the
		edit cell name and the total number of errors found.  With
		<B>total</B>, returns just the count as an integer.
	   <DT> <B>find</B> [<I>nth</I>]
	   <DD> Return the error description of the next, or <I>nth</I>,
		error to the interpreter.
	   <DT> <B>why</B>
	   <DD> Return the error description of all errors intersecting the
		cursor box to the interpreter, as a list
	 </DL>
      </BLOCKQUOTE>

      <B>drc listall</B> <I>option</I> <BR><BR>
      <BLOCKQUOTE>
         where <I>option</I> is one of the following:
	 <DL>
	   <DT> <B>style</B>
	   <DD> Return a list of all available DRC styles to the interpreter.
	   <DT> <B>count</B> [<B>total</B>]
	   <DD> Return the DRC error count as a nested list, where each list
		item is a pair comprising the cell name of the cell containing
		the errors, and the total number of errors found.  With
		<B>total</B>, returns only the sum of all the values (probably
		not very useful).
	   <DT> <B>why</B>
	   <DD> Return a nested list containing a detailed description of all
		errors intersecting the cursor box to the interpreter.  In the
		topmost list, every other entry is the text description of a
		DRC error class.  The list item following the DRC error
		description is a list of all errors of that type.  Each error
		is presented as a list of four values indicating the bounding
		box of the error, as {<I>llx lly urx ury</I>} values in
		internal database units.
	 </DL>
      </BLOCKQUOTE>

   </BLOCKQUOTE>

<H3>Summary:</H3>
   <BLOCKQUOTE>
      The <B>drc</B> command controls the behavior of magic's "background"
      design rule checker.  Normally the design rule checker is invoked
      whenever the design is changed and checks all parts of the design
      close to the changed area that might have been affected by the
      change.  The design rule checker flags areas that have been checked
      as it runs.  It starts whenever a layout change has been made or
      after any command has been executed if areas of the layout still
      need to be checked.  Any macro keystroke in the layout window or
      command executed on the command line will interrupt the design
      rule checker pending completion of the action, at which time
      the design rule checker will be reactivated. <P>

      The <B>drc on</B> and <B>drc off</B> options are the main controls
      for starting and stopping the design rule checker.  <B>drc status</B>
      returns the status of the background checker, either "on" or "off".
      The Tcl version of magic returns a boolean value (0 or 1). <P>

      The <B>drc check</B> option marks all areas of the layout under the
      box as requiring a check and restarts the design rule checker. <P>

      The <B>drc why</B> and <B>drc find</B> commands can be used to
      query errors in the layout discovered by the design rule checker.
      <B>drc why</B> reports the reason for all error regions found
      inside the <B>magic</B> cursor box.  The <B>drc find</B> command
      can be used to find errors that may not be visible inside the
      current window view, or that may be difficult to find on a large
      layout. <P>

      The <B>drc euclidean on</B> command can be useful in cases where
      vendor design rules intend a Euclidean distance metric (minimum
      linear distance) rather than a Manhattan distance metric (minimum
      distance in either the <B>x</B> or <B>y</B> direction, evaluated
      separately).  The default option is "off", as most vendor rules
      and design rule checkers assume Manhattan distances when checking
      rules. <P>

      The remaining options are relativly obscure and unlikely to be
      useful to the typical end-user.</P>
   </BLOCKQUOTE>

<H3>Implementation Notes:</H3>
   <BLOCKQUOTE>
      <B>drc</B> is implemented as a built-in <B>magic</B> command.
   </BLOCKQUOTE>

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<P><I>Last updated:</I> March 7, 2020 at 1:06pm <P>
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